Intermediates and process for insecticidal biphenylmethyl esters

ABSTRACT

Compounds of formulae II, III and IV: ##STR1## are useful intermediates for preparation of an insecticidal compound of formula (I) ##STR2## in which R a  and R b  are independently hydrogen, halogen, or alkyl. The intermediate II is prepared by reacting 3,3-dimethyl-4-pentenoic acid, a salt thereof, a lower alkyl ester or an acid chloride thereof with a compound of the formula ##STR3## in which X is hydroxy or a good leaving group. Intermediate III is prepared by reacting II with 1,1,1-trichloro-2,2,2-trifluoroethane in the presence of a solvent and catalyst. Intermediate III is then dehydrohalogenated in the presence of base to remove 2 moles of halogen halide per mole of III in one or two steps to produce I.



